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Thursday, October 1, 2015

Ariane 5 Rocket Sends Two Communications Satellites into Orbit

An Ariane 5 rocket successfully launched on Wednesday, Sept. 30, with a pair of communications satellites for Argentina and Australia. Lift-off took place at 4:30 p.m. EDT (20:30 GMT) from the Ariane Launch Area 3 at the European spaceport located in Kourou, French Guiana. The mission, conducted by the commercial launch services provider Arianespace, was designated Flight VA226.

The countdown for Wednesday’s launch started some 11 hours and 30 minutes before the scheduled lift-off time. Electrical systems were checked and about five hours ahead of the launch the filling of the main cryogenic stage with liquid oxygen and hydrogen was initiated. The countdown culminated in a synchronized sequence, which is managed by the control station and onboard computers starting at T–7 minutes. The connections between launcher and telemetry, tracking and command systems were also tested and just minutes before the boosters ignition, the Ariane 5 rocket was given the green light to start the mission.

After lift-off, the rocket climbed vertically for about 12 seconds before the booster’s pitch maneuver was initiated. The vehicle’s solid boosters separated two minutes and 21 seconds into the flight, and exactly one minute later the fairing was jettisoned. The separation of the main cryogenic stage occurred nearly nine minutes after the launch, clearing the way for the upper stage to ignite its HM7B engine.

The cryogenic upper stage, named ESC-A, continued its flight for an orbital injection that took place about 25 minutes after lift-off. Then it was ready to deploy its two passengers – the Australian Sky Muster and the Argentinian ARSAT‑2 satellites. The Sky Muster spacecraft was released first at T+28 minutes, while ARSAT-2 separated about four and a half minutes later.

The main cryogenic stage fell back into the Atlantic Ocean after separation, breaking up at an altitude of between 50 and 37 miles (80 and 60 km) under the loads generated by atmospheric re-entry.

Sky Muster and ARSAT-2 are the 517th and 518th satellites launched by Arianespace. Both spacecraft were placed into a geostationary transfer orbit (GTO). During the flight, the launcher’s attitude and trajectory are entirely controlled by the two onboard computers in the Ariane 5 vehicle equipment bay (VEB).

The launch campaign started in August 2015 when the satellites arrived in Kourou. They were fueled and integrated on the payload adapter in mid-September. Payload integration activity took place at the Ariane 5’s Final Assembly Building, where both spacecraft were readied for the lift-off. The launch readiness review was conducted on Monday, Sept. 28, while the rocket’s rollout to the launch pad occurred one day later.

Sky Muster, weighing nearly 6.4 metric tons, is one of the world’s largest communications satellites. It will be operated by NBN, an Australian government-owned telecommunications corporation. The satellite was built by Space Systems Loral (SSL) of Palo Alto, California using the company’s well-renowned 1300 platform.

Sky Muster has 202 Ka-Band transponders and is planned to be functional for more than 15 years. It is a high-throughput broadband satellite that uses multiple spot beams in an advanced design.

The satellite was designed to enable NBN to deliver broadband services to more than 200,000 rural and remote Australians. It will extend coverage to the entire country, including Norfolk, Christmas, Macquarie, and Cocos Islands.

The spacecraft, formerly known as NBN Co 1A, received the nicknameSky Muster in May 2015, which was selected from hundreds of entries as the winner of the nationwide competition for school children. The children were also asked to provide an original painting or drawing that illustrates how the NBN network will make Australia a better country. Six-year-old Bailey Brooks was the national winner; she provided the name for the spacecraft, and her drawing has been reproduced on the Ariane 5’s payload fairing.

The second NBN satellite – NBN Co 1B – is planned to be launched by Arianespace on a future mission. It will be the next step for the company in building a new, fast broadband network to reach all communities across Australia. NBN’s goal is to connect eight million homes and businesses by 2020.

ARSAT-2 is a geostationary communications satellite operated by ARSAT telecommunications company and built by the Argentine company INVAP. The spacecraft is the second in a series of geostationary (GEO) satellites that gives Argentina its own space telecommunications system. ARSAT-2 will provide North and South American countries with direct-to-home television (DTH), Internet access services for its reception on VSAT antennas, data transmission, and IP telephony.

Weighing about three metric tons, ARSAT-2 is the second GEO satellite to be built in Argentina. As with the ARSAT-1 satellite, the Launch and Early Orbit Phase (LEOP) will be performed from ARSAT’s Benavídez Ground Station. It will be the second time that a Latin American country will run an operation of this kind.

The ARSAT-2 satellite is equipped with 26 Ku-Band transponders and 10 C-band transponders. It is designed to be operational for 15 years. It will be the second satellite orbited by Arianespace for the ARSAT company, following ARSAT-1’s successful launch on Oct. 16, 2014.

The spacecraft is a part of the Argentine Geostationary Telecommunications Satellite System. This program includes the design and manufacture of three ARSAT satellites, sending them into orbit, and their operation. The aim of which is to increase the telecommunications capacity of the country and to guarantee the same level of connectivity quality to all its regions.

Ariane 5 in ECA configuration that was used in the launch is the heavy-lift rocket for missions to GTO and usually carries two telecommunications satellite payloads. It is powered during the initial flight phase by a cryogenic core stage and two solid rocket boosters, followed by the use of a cryogenic upper stage for orbital injection of the payload.

The 180 ft. (54.8 m) tall ECA is an improved version of the Ariane 5 launcher, designed to deliver payloads, mainly communications satellites, weighing up to 10 metric tons. Although it has the same general architecture, some significant changes were made to the basic structure of the generic version to increase thrust and enable it to carry heavier payloads.

ECA is also used by institutional customers for non-GTO missions; for example, launching ESA’s Herschel and Plank scientific missions in 2008.

Wednesday’s mission was the 226th liftoff of an Ariane vehicle from the Kourou Spaceport. It was the fifth Ariane 5 launch of 2015 (82nd Ariane 5 launch overall), and the ninth of 12 flights planned this year by Arianespace utilizing its family of the heavy-lift Ariane 5, the medium-lift Soyuz, and the lightweight Vega.

Arianespace’s next launch is scheduled for Nov. 5 when it is expected to send into orbit the Arabsat 6B satellite for Arabsat and the GSAT-15 spacecraft for the Indian Space Research Organisation.